When you install a default instance of Microsoft® SQL Server™ 2000, the standard network addresses are enabled. For example, named pipes uses \\.\pipe\sql\query, and TCP/IP sockets connect to port 1433.
When you select a named instance, only the Named Pipes, TCP/IP, and NWLink IPX/SPX protocols are supported. Named Pipes defaults to a network address of \\Computername\Pipe\MSSQL$instancename\Sql\Query. The port addresses used by TCP/IP and NWLink IPX/SPX are chosen dynamically (by default) the first time the instance is started.